In the technical context in question buckets that can be fitted on the end of an arm of an operating machine, comprising an outer casing configured for the collection of inert material such as gravel, material resulting from the demolition of buildings, within which members for crushing the material collected is mounted, are known.
One example of this type of bucket is described in European Patent EP 1532321, in which the bucket is spoon-shaped and the crushing members take the form of a pair of jaws which act with an alternating movement on the material to be crushed.
In these buckets an opening is normally provided for the material to be crushed, into which the material is inserted by causing the bucket to act as a gathering shovel through suitable movement of the arm of the operating machine.
From International Patent Application WO 2006105864 it is also known that screening devices can additionally be provided on the outer casing at the entrance to the bucket in addition to the crushing members.
The screening devices take the form of a perforated plate which forms the bottom of the opening through which the material being crushed enters and on which the material is spread out after it has been gathered. The plate is associated with a vibrating system to cause it to vibrate and allow material of small size to fall through.
After the initial screening the bucket is raised, allowing the material to fall into the crushing zone in a manner which is conceptually similar to that of other known buckets.
This combined screening and crushing system requires two different motor units to operate it, with little optimisation from the energy point of view, and in any event it is not very practical for the operator of the operating machine who has to control movement of the excavator arm and the corresponding two controls for activating the motor units at the same time. In addition to this the stages of screening and crushing, one after the other, are not in any way coordinated during operation of the bucket, thus making this solution of little practicality in use, and in fact causing it to be difficult to apply on an industrial level.